Start:

Old rail and stile doors, also called raised
panel doors, have a tendency to come apart. I believe most of
these doors were glued together during manufacturing, so it's no
surprise that the glue might fail after a century or so.

A bathroom door in this turn-of-the-last-century house had a bad
case of separated sections. I suspect that the previous owners had
long been dealing with a door that wouldn't shut, which does not
make for good privacy. I decided to try fixing it, and I was
surprised how easy it was.

At the top of this old solid-wood door there was
a big gap between the stile (the vertical side board) and the
rail (the horizontal cross-piece).

Memory Aid: Rails
are like ladder Rungs.

The gap, about 1/4", was especially visible
from the end.

I used a tiny screwdriver to clean out the dust
and dirt from the gap.

I applied a 5 foot long pipe clamp across the
top of the door, just to see if it would be possible for the
pieces of wood to fit together. I figured that something would
jam up and prevent the pieces from mating smoothly.

I tapped on a scrap of wood to make some
vibrations. This can make a big difference in how easily tight
pieces of wood fit together.

I was surprised. The sections went together
perfectly. It appeared that the top rail had slipped down in
some other position for a while, judging by the marks on the
finish (red arrow).

The gap closed right up. I was tempted to just
drill some holes and screw this joint together, but I wanted
to glue the joint too.

So I shoved a screwdriver into the joint and
pried the pieces back apart.

I squeezed some carpenter's glue into the gap.

Then I used a tiny screwdriver to spread the
glue.

Note that the raised panels are NOT supposed to be glued to
the rails and stiles. The panels are supposed to be free to
move slightly.

I applied pressure with the pipe clamp and wiped
off the excess glue with a wet rag.

Note the wood blocks used between the clamp and the door.
These prevent the clamps from crushing the wood and leaving a
dent.

The Real Holding Power:

I laid a 1-1/2" long sheet metal screw on
the face of the door to check the ideal placement. The screw
head will need to be buried in the wood so it never interferes
with the closing of the door.

I used a 3/8" spade drill bit to make a
pocket hole.

I have this fancy Kreg Pocket Drill kit, which drill holes at an
extremely low angle, but I forgot it at home. So I had to improvise
with the tools on hand.

It's impossible to start a spade bit at a low
angle, so I started drilling almost perpendicular to the end
of the door.

Once the drill was started I leaned the bit over
to the low angle I wanted.

I made two quick holes. I tried to angle the
holes away from the face of the doors, so the drill bit would
not break through the surface.

Then I drilled a pilot hole with a long thin
bit. I can't remember the diameter of this bit, it might be
3/32".

Then I drilled a larger clearance hole. This
hole only goes through the first piece of wood.

I drove the screws in.

The heads were buried in about 1/4" of
wood.

The door fit perfectly in the door opening.

The arrow indicates where the door was hitting. I wonder
how many cumulative minutes and hours of nuisance the previous
occupants endured from this rather minor problem.

I have some old rail-and-stile doors with similar separation
problems, but they have been painted over many times. Removing old
paint from the gap could be 3 or 4 times as much work as fixing the
gap.